Flexible wood floor or flooring material



July 12, 1938. A. ELMENDORF 2,123,409

FLEXIBLE WOOD FLOOR OR FLOORING MATERIAL Filed Dec. 10, 1956 2 Sheets-Sheet 1 July 12, 1938. A. EILMENDORF FLEXIBLE WOOD FLOOR OR FLOORING MATERIAL Filed Dec. 10, 1936 2 Sheets-Sheet 2 l ii Patented July 12, 1938 UNITED STATES ,aizaaoo FuixmLa woon noon. on noosma m'rsam.

Armin Elinendorf, Winnetka, m. Application lleceinber 10, 1936, Serial No. 115.504

20mins.

There is a constantly increasing demand for line wood floors laid upon and covering concrete subfloors. The most common practice is to cover the subfloor with a layer of plastic binding material such as asphalt, for example, and to press down into the same wood blocks or short boards, arranged side by side, until the entire floor surface is covered with pieces of wood arranged in various patterns or designs. There are various serious objections to thistype of floor because the individual pieces of wood are not eifectively anchored and, as expansion and contraction cccurs, due to changes in the moisture content of the wood, there is a continual bodily shifting of the individual pieces in the plane of the floor, causing the floor as a whole, or large sections thereof, to move. This shifting of the wood layer results in the opening of cracks or the widening of open joints while other joints are narrowed; 20 and, sometimes, a sufficient lateral pressure develops to cause room partitions to become displaced.

The object of the present invention is to produce a simple and novel floor or flooring material which mayoverlie a concrete or other subfloor and'provlde awearing layer of wood which remains stationary upon the subfloor although each piece of wood therein is permitted to expand and contract naturally while eflectively 30 anchored to the subfloor.

Others have heretofore produced flexible woodfaced floor coverings by gluing wood blocks or short boardsto paper or cloth backings the main function of which is to hold the wood pieces toby assembling the constituent elements and building up my improved floor upon the subfloor, or in preforming sheet flooring that maybe laid in sections of any desired sizes. Therefore, viewed in one of its aspects, the present invention may be said to have for its object to produce a novel and durable floor or flooring in which individual pieces of wood are bonded to a flexible backing and in which the nature of the structure is such 9 that the wood does not warp or tear itself loose from the backing.

When others have bonded wood tiles to a flexlble backing, this has been done with an adhesive which not only sets and hardens but penetrates 55 the backing material and causes it to become hard and board-like. When such a flooring material .is in use, the changes in moisture content. of the wood cause the wood to expand and contract. The board-like backing constrains the under side of each tile so that with an increase 5 in moisture content, the top of each tile expands and causes the tile 'to take a convex shape. 80, also, when the moisture content-of the wood is low, the upper portions of each tile contract and cause the top surface to assume a concave shape. This alternate flexing or bending of the tiles, first in one direction and then in the other, soon disrupts the joints between the tiles and the backing and also tears the backing loose from the sub floor if it has been bonded to the latter.

In accordance with my invention, the pieces of wood, whether they be blocks or short boards up to such lengths as are commonly employed in making herringbone floor designs and to which I shall hereinafter refer as tiles, are anchored to the subfloor but are not prohibited from expanding and contracting in a natural way. This I accomplish by employing a backing. membrane having a capacity for appreciable internal shear displacement; bonding the tiles to this membrane in such a manner that this capacity of thelatter is not destroyed; and bonding the membrane to the subfloor, also in such a manner that the membrane retains its normal characteristics. The adhesive or bonding material between 30 the tiles and the backing membrane must not be of a. kind that remains plastic and permits the tiles to shift bodily, but must be of a character to prevent such bodily shifting. Adhesive suit able for the purpose must therefore be hard or elastic during the time the floor is'in use. I prefer that the adhesive be of the elastic type.

It therefore follows that in the use of the floor, if the tiles become dry so that their moisture content is considerably less than it was at the time the floor was laid, the tiles simply contract and open the joints between adjacent tiles a little wider. Since the backing membrane is not rigid but is suflicientlyylelding to permit therein thenecessary shear displacement to compensate for the shrinkage in the wood,the tiles do not warp and present concave upper surfaces; and, therefore, the tiles'do not tear themselves loose from the backing membrane, nor do they tend to pull the membrane away from the subfloor. On the other hand, should the tiles, after being laid, take up moisture, they simply expand and close the joints, still remaining flat and eflfectively anchored to the subfloor. In neither case does the change in dimensions of any tile effect 56 to a greater or lesser extent prevent relative vertical movements. Such an arrangement has the advantage that each tile is held in the plane of the wood layer by the tiles bordering upon or immediately surrounding the same and reduces the danger that a tile may, for example, be kicked. loose, if, in finishing the floor that tile may have been left projecting slightiyabove an adjacent tile. This interconnection may be accomplished by mechanical interlocks or by yieldable bonding material in the joints. Such bonding material may fill a networkof grooves following the joints between the tiles and, as long as it is of a plastic or elastic character, will permit the tiles to expand and contract while offering considerable resistance to a kick, blow or shock tending to drive a tile upward.

The various features of novelty whereby my vinvention is characterised will hereinafter be pointed out with particularity in the claims; but, for a full understanding of my invention and ofits objects and advantages, reference may be hadto the following detailed description taken in connection with the accompanying drawings, wherein: I

Figs. 1 and 2 are sectional'views, more or less diagrammatic, illustrating the common practice of setting tiles in a mastic bed covering a subfloor, the shapes of the tiles being different in the two figures; Figs. 8 and 4 are edge views of a tile' glued to a hard constraining backing, illustrating conditions that are brought about, respectively, by an increase in the moisture content and by a drying out of the tile; Figs. 5 and 6 are sections, more or less diagrammatic, showing fragments of my improved floor, Fig. 5 illustrating the iloor as it'is under moisture conditions corresponding to that of Fig. 3. and Fig. 6 illus-' trating what takes place under moisture conditions corresponding to that of Fig. 4; Figs. 7, 8 and 9 are plan views of fragments of doors embodying the present invention, each representing a different design or pattern of tiles; Figs. 10, 11 and 12 are vertical sections, illustrating three slightly different modifications of my improved iloor, only -fragments of the floor and subiloor being shown in each instance; Fig. 13 is a section on a much smaller scale, .on line I3-l3 of Fig. 11, illustrating a fragmentof one of the tiles which is assumed to be in the form of a board; and Fig. 14 is a section, on a much smaller scale, on line l4--l4 of Fig. 12, illustrating, one of the tiles which is assumed to be in the form of a little block.

Referring to Fig. l of the drawings, A represents a subfloor and B, B, represent wood tiles set upon the. suhfloor in a bed C of mastic, usually asphalt. The tiles are interlocked by means of complementary tongues and grooves D and E, respectively. The mastic extends up into grooves or recesses I" in the under faces of the tiles; the intent being to provide keys to hold the tiles down. Obviously, keys of plastic material are not very effective as long as the entire anchoring means for each tile consists of a plastic material. In any event, itis evident that the tiles, in expanding and contracting, or when sub- Jected to forces of any kind that tend to move them laterally, can move bodily across the subiloor. Bincesometilesmaymoveinonedirection and others in another direction, unsightly cracks may, and eventually do, open. A common type of floor that is even less satisfactory is shown in Fig. 2, in which the tiles G, G are keyed together by a plastic material C entering grooves or recesses H in the bottom face of the t e layer. This floor is open to the same obj. tions as that in Fig. 1 and is even less satis-- factory than the latter because of the lack of mechanical interlocks between tiles.

In Figs. 3 and 4 there is illustrated a common type of floor covering in which the tiles B are glued to a flexible backing I. The usual glues employed in securing the tiles in this form of I material penetrate the fabric backing and harden it. While it might be possible to prepare a piece of fabric such as burlap or canvas, to prevent it from being soaked when the tiles are glued to the same, so far as I am aware, this has never been done in this old type of floor covering. The result is that when the tile takes up moisture, the upper part thereof expands while the lower face is constrained by the hard stin backing, and the tile bulges upwardly, as shown in Fig. 3. When the tile becomes very dry. the upper part shrinks while the under face still remains constrainedand, therefore, the tile takes the concave shape shown in Fig. 4. It is evident that if a floor covering of this kind is glued to a subiloor, the tiles will tear themselves loose and will also disrupt the joint between the backing and the subfioor. Consequently, the use of such floor coverings has been confined to wood subiloors to which they can be nailed, and the fleld of concrete floor coverings is closed to this type of covering.

In Figs. 5 and B I have illustrated the principle of my invention. The tiles K are bonded to a backing membrane L by a layer of adhesive M. The backing membrane must have considerable body and it must be of a character that permits appreciable internal shear displacement during the use of the floor. The simplest and least expensive material for this purpose is felt. Where felt is employed, it preferably has a thickness of about one-twentieth of an inch or more. The layer of bonding material M between the tiles and the backing membrane should be as thin as may be and, if this material was plastic before or during the time of making the bond, it must afterwards be non-plastic. While the bonding layer M may be of the hard and tough type, I prefer that it be composed of an adhesive having a base of rubber latex and thus be elastic during the use of the floor. The backing membrane is secured to the subfloor by a layer of any suitable bonding material N, meaning by this any material which, through the process of bonding the membrane to the subiioor, does not destroy or objectionably lessen the capacity for internal shear displacement in the membrane. -When the moisture content of the tiles is at the maximum, during the use of the floor, the joints may be completely closed, as indicated in Fig. 5. When the floor becomes dry, each tile contracts and draws away from the surrounding tiles, thereby producing open joints between adjacent tiles, as indicated at k in Fig. 6. Since the tiles, whether they be blocks or boards, are always narrow crosswise of the grain, the actual changes in dimensions of an individual tile are not great and therefore no wide Joints will appear at any time. In the case of a floor where the tiles may shift or creep bodily in a lateral direction, the eflect of contraction or expansion of the tiles upon joints frequently is cumulative, so that wide cracks are caused to appear. However, in my floor the width of each joint depends solely upon the amount of expansion and contraction that takes place in the two tiles on opposite sides of the joint; the upper stratum of the backing membrane yielding, as indicated at I in Fig. 6, upon contraction of the tiles, to permit the center of each tile to remain stationary during the narrowing of the tile. Conversely, when the wood again takes up moisture, the tiles simply widen out again, their centers still remaining stationary.

The actual tiles may be in the form of short boards I as indicated in Figs. 7 and 8, or may be little blocks, such as shown at 2 in Fig. 9.

It is advisable that there be some interlock or connection between adjacent tiles, whereby each tile aids in holding down adjacent tiles, without destroying the principle of independence of expansion and contraction. Thus, in Fig. 10, the tiles are provided with complementary tongues and grooves 3 and l which cooperate in the usual way to hold meeting tiles against relative displacements at right angles to the plane thereof. These joints or connections, however, do not offer any opposition to natural expansion or contraction and have no tendency to force any tile out of its normal position. The tongues and grooves not only serve as interlocks but they also make it more difficult for water to reach the backing membrane from above than if simply butt joints were employed.

As heretofore stated, the backing membrane L may advantageously consist of felt, one-twentieth of an inch thick, or thicker, which felt may be saturated with asphalt or other suitable water-proofing material which does not harden the felt; or it may consist of a suitable, properly prepared fabric. The bonding layer M between the wood and the backing membrane should be as thin as is consistent with securing a satisfactory bonding of the tiles. Otherwise, any suitable material may be used for this purpose, as long as it does not penetrate the backing membrane and make it hard and stiff and as long as it does not remain plastic and permit the tiles to creep. I prefer, however, that the bond between the tiles and the backing membrane be elastic. when the bonding layer M is composed of an adhesive having a rubber latex base, the desirable characteristic of elasticity is secured and the other requirements ,for a satisfactory bonding material are adequately met. The bonding layerN between thebacking membrane and the subfloor may be almost any adhesive substance, as long as it is sufficiently strong and lasting and does not harden the interior of the backing membrane. Therefore, while I prefer to use a paste such as that with which linoleum is commonly fastened down, even a bonding material that remains plastic. such as asphalt, will do.

8 in the tiles. The depth or thickness of the grille, corresponding to the vertical dimensions of the grooves, is small compared with the thickness of the tiles, so that the vertical cross section of the bond between two meeting tiles is of comparatively small area, and the resistance that the bond between two tiles can offer to norresistance to such displacement. In other words,

even though the material of the grille be such that no very great force is required to cause it to yield under a slow and steady push or pull; yet, under a sudden blow, it acts in the manner of a rigid structure and exerts a holding power comparable to that of the tongue in Fig. 10 and the spline or key in Fig. 11.

I claim:

1. A floor comprising a subfloor, a membrane made from material that provides it with capacity for appreciable internal shear displacement bonded to the subfloor, wood tiles overlying the said membrane and arranged edge to edge, the tiles being connected together by tongues and grooves membrane and arranged edge to edge, means including stifi elements extending across the joints from one tile to another at points between the upper and lower faces of the tiles mechanically interlocking the tiles in a manner to permit each tile to expand and contract laterally independent- 1y of adjacent tiles, and a bonding material in a non-plastic state holding the tiles to the said membrane. i g

ARMIN EIAIENDORF. 

